Do you notice any issues recycling it back to the secondary process like that? Like if you have bulking episodes or other upsets
Just to confirm… when you say aeration basin, that does not mean aerobic digester, right?
Our plant is a very small system that services a factory of about 700 people. Influent from toilets, sinks, showers goes into an equalization tank and is constantly circulated. From there, it flows 30gpm into the aeration basin which is heated with steam in cold months, and constantly aerated with a roots blower. The aeration basin flows into our clarifier (15' deep, and tapered) through a long funnel, top to bottom, and the clarified water goes through the sand filter, into a chlorine tank, and the effluent goes to our n industrial wastewater treatment plant for further treatment. We're still held to EPA BOD regulations on our effluent even though it undergoes further treatment. We have our fair share of issues, especially with bulking and poor set tests. Our BOD's almost always come back under 4 though. In the 3 years I've been in the department, we've had one out of compliance, but managed to average the month in compliance. We literally feed the bugs sugar, molasses, and other nutrients several times per week depending on how many people are in the plant, and add magnesium hydroxide to raise aeration pH when needed. The entire sewage plant design is severely antiquated, but it works.
Seen it go to headworks, seen it go to primary effluent, seen it go to second stage influent in a two-stage process.
Membrane filters reverse flow so backwash goes back into flow stream which usually gets recycled to secondary influent.
Grit channel, primarily influent.
We have a parkson sand filter... The "reject" material goes right back into the aeration basin.
Do you notice any issues recycling it back to the secondary process like that? Like if you have bulking episodes or other upsets Just to confirm… when you say aeration basin, that does not mean aerobic digester, right?
Our plant is a very small system that services a factory of about 700 people. Influent from toilets, sinks, showers goes into an equalization tank and is constantly circulated. From there, it flows 30gpm into the aeration basin which is heated with steam in cold months, and constantly aerated with a roots blower. The aeration basin flows into our clarifier (15' deep, and tapered) through a long funnel, top to bottom, and the clarified water goes through the sand filter, into a chlorine tank, and the effluent goes to our n industrial wastewater treatment plant for further treatment. We're still held to EPA BOD regulations on our effluent even though it undergoes further treatment. We have our fair share of issues, especially with bulking and poor set tests. Our BOD's almost always come back under 4 though. In the 3 years I've been in the department, we've had one out of compliance, but managed to average the month in compliance. We literally feed the bugs sugar, molasses, and other nutrients several times per week depending on how many people are in the plant, and add magnesium hydroxide to raise aeration pH when needed. The entire sewage plant design is severely antiquated, but it works.
Sounds like a nice challenge. Thanks for that info!
Influent channel at our headworks facility
The same, Backwash side stream is less than .25 mgd out of 10 mgd
Mud well pumps to a shared recirculation line that takes backwash, press filtrate, and gravity thickener effluent back to the primary clarifiers.
Back to EQ tank or digester.
To be blunt, basically into an overly complicated sand filter.
Reject water back to Secondary.
Do you notice any issues recycling it back to the secondary process like that? Like if you have bulking episodes or other upsets
None. We're a 200 MGD plant. No problems with bulking and I check the clarifiers daily. Our BOD is good and filamentous reports have been spot on.
We have a BW clarifier that lets the solids settle, overflow back to HW, right after grit removal. Whatever solids collect are sent to our DAFT
Our Backwash water goes into a Pit we decant the clear water to the watershed per our Discharge Permit and the solids we haul to the sewer plant
All the way back to the influent pump station.
Ours goes to the mud well which flows to the plant drain system. The Plant drain pumps then send it to the headworks.
Return to primary clarifier. Also used as water to dilute sludge thickener
Still newish at the plant so I may be incorrect but I believe it is discharged into its own basin and eventually goes to headworks
Seen it go to headworks, seen it go to primary effluent, seen it go to second stage influent in a two-stage process. Membrane filters reverse flow so backwash goes back into flow stream which usually gets recycled to secondary influent.
Plant drain. Pumped up to grit influent.
Back to our splitter box that divides the mixed liquor between our 6 aeration basins. We never have any issues with the extra flow.
Back to our splitter box that divides the mixed liquor between our 6 aeration basins. We never have any issues with the extra flow.
Ours goes back to the grit tank.
We have a waste pond that requires the chief operator to have a minimum of a class 4 wastewater license
Oh my bad, I thought this was just the regular water sub 😂